Health risk from Japan reactor seems quite low: WHO http://in.reuters.com/article/2011/03/12/us-japan-quake-health-who-idINTRE72B2XK20110312 GENEVA | Sat Mar 12, 2011 11:46pm IST
(Reuters) - The World Health Organization (WHO) said Saturday that the public health risk from Japan's radiation leak appeared to be "quite low" but the WHO network of medical experts was ready to assist if requested.
"At this moment it appears to be the case that the public health risk is probably quite low. We understand radiation that has escaped from the plant is very small in amount," World Health Organization spokesman Gregory Hartl told Reuters.
Radiation leaked from an earthquake-crippled nuclear plant in Japan Saturday after a blast blew off the roof, and authorities were preparing to distribute iodine to local people to protect them from exposure.
0545: The situation at the damaged Fukushima plant is still developing but Malcolm Grimston, an expert on the nuclear industry from Imperial College London, argues that the Japanese authorities should be proud of their foresight. "Given the circumstances, I think this is an extraordinary tribute to those scientists and engineers and designers who built these plants in the 1960s. I'm enormously impressed at the way in which these reactors have withstood the largest earthquake ever in Japan and one of the 10 largest that we've ever recorded on earth".
Expert sees "good news" in Japan nuclear fight http://www.reuters.com/article/2011/03/13/us-japan-quake-nuclear-expert-idUSTRE72C35920110313
(Reuters) - Japan struggled on Sunday to limit the damage at earthquake-crippled nuclear power reactors, but experts said a bigger disaster could be averted.
Japanese authorities "appear to be having enough success to have forestalled a definite core melt accident that's difficult to control," said Mark Hibbs of the Carnegie Endowment for International Peace. "After three days that is very good news."
1726: IAEA chief Yukiya Amano says the nuclear crisis in Japan is unlikely to turn into another Chernobyl. Mr Amano is still answering questions at a press conference in Vienna. The accident at Chernobyl in 1986 remains the world's worst nuclear accident.
The term "meltdown" is used in a variety of ways. As noted above, the reported detection of radioactive caesium and iodine may indicate that some of the metal casing enclosing the reactors' uranium fuel has melted (a "fuel-rod meltdown"). However, there is as yet no indication that the uranium fuel itself has melted. Still less is there any indication of a "China Syndrome" where the fuel melts, gathers below the reactor and resumes a chain reaction, that enables it to melt everything in its way, and bore a path deep into the earth. If there were to be a serious meltdown, the Japanese reactor is supposed to be able to handle it, preventing the China Syndrome from taking place. Reports suggest that underneath the reactor, within the outer containment vessel, there is a concrete basin designed to capture and disperse any molten fuel. 「メルトダウン」という語は様々な意味で使われている。指摘したように、放射性セシウムと ヨウ素の検出という報告はウラン燃料の金属被覆の一部が融解したことを示している。 (燃料棒メルトダウンと言っても良い) しかし今のところウラン燃料それ自身が解けたいかなる兆候もない。ましてチャイナシンド ロームのいかなる兆候もない。 たとえシリアスなメルトダウンが起きたとしても、日本の原発はチャイナシンドロームに至らないよう 対処できると思われる。 報告によると、外部格納容器の中の反応炉の下部にコンクリートの皿があり、いかなる融解燃料も 受け止めて分散しうるよう設計されている。
Fukushima Nuclear Accident ? a simple and accurate explanation http://bravenewclimate.com/2011/03/13/fukushima-simple-explanation/
The third containment is designed, built and tested for one single purpose: To contain, indefinitely, a complete core meltdown. For that purpose, a large and thick concrete basin is cast under the pressure vessel (the second containment), which is filled with graphite, all inside the third containment. This is the so-called “core catcher”. If the core melts and the pressure vessel bursts (and eventually melts), it will catch the molten fuel and everything else. It is built in such a way that the nuclear fuel will be spread out, so it can cool down.